Light emitting device, super-luminescent diode, and projector

ABSTRACT

A light emitting device includes a substrate, a laminated body formed by stacking a first cladding layer, a first active layer, a second cladding layer, a third cladding layer, a second active layer, and a fourth cladding layer on the substrate in this order, a first electrode connected to the first cladding layer, a second electrode connected to the second cladding layer and the third cladding layer, and a third electrode connected to the fourth cladding layer, the first active layer generates first light using the first electrode and the second electrode, the second active layer generates second light using the second electrode and the third electrode, and a side surface of the first active layer is provided with an emitting section for emitting the first light, and a side surface of the second active layer is provided with an emitting section for emitting the second light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation patent application of U.S. application Ser. No.13/886,696 filed May 3, 2013, which claims priority to Japanese PatentApplication No. 2012-107959, filed May 9, 2012, all of which areexpressly incorporated by reference herein in their entireties.

BACKGROUND

1. Technical Field

The present invention relates to a light emitting device, asuper-luminescent diode, and a projector.

2. Related Art

A super-luminescent diode (hereinafter also referred to as an “SLD”) isa semiconductor light emitting element, which is capable of providing anoutput up to several hundreds of mW with a single element similarly to asemiconductor laser while having a broad spectrum and thus beingincoherent similarly to an ordinary light emitting diode.

The SLD is used as, for example, a light source of a projector. Forexample, there has been proposed a system of a projector disposing eachof the SLD for emitting red light, green light, and blue lightimmediately below a light valve, and simultaneously performing controlof the emission angle of the light (collection, collimation, and so on)and uniform illumination using microlenses. It is desirable in such aprojector to form two or more colors of light sources (out of the threecolors) on the same substrate in order to achieve common use of theoptical system for miniaturization and cost reduction of the projector.

For example, JP-A-2002-299750 discloses a technology of forming twosemiconductor lasers with respective wavelengths on the same substrate.

By using the technology described above, it is possible to form thesemiconductor lasers or the SLDs respectively having two colors of blueand green on the same substrate.

However, in the light emitting device described in the patent documentmentioned above, an n-side electrode and a p-side electrode forinjecting current into an active layer are formed on the both sides ofthe light emitting device across the active layer and the substrate.Therefore, there is a problem that the layout of the wiring lines to beelectrically connected to the electrodes is made complicated and ahigher mounting cost is required when mounting the light emittingdevice.

SUMMARY

An advantage of some aspects of the invention is to provide a lightemitting device which makes the layout of the wiring lines to beelectrically connected to the electrodes easy and simple when mounting.Another advantage of some aspects of the invention is to provide asuper-luminescent diode which makes the layout of the wiring lines to beelectrically connected to the electrodes easy and simple when mounting.Still another advantage of some aspects of the invention is to provide aprojector including the light emitting device described above or thesuper-luminescent diode described above.

Alight emitting device according to an aspect of the invention includesa substrate, a laminated body formed by stacking a first cladding layer,a first active layer, a second cladding layer, a third cladding layer, asecond active layer, and a fourth cladding layer on the substrate inthis order, at least one first electrode electrically connected to thefirst cladding layer, a second electrode electrically connected to thesecond cladding layer and the third cladding layer, and a thirdelectrode electrically connected to the fourth cladding layer, the firstelectrode, the second electrode, and the third electrode are located onan opposite surface of the laminated body to the substrate, the firstactive layer generates first light in response to current injected usingthe first electrode and the second electrode, the second active layergenerates second light in response to current injected using the secondelectrode and the third electrode, and at least one side surface of thefirst active layer included in a side surface of the laminated bodyhaving a normal line perpendicular to a stacking direction of thelaminated body is provided with an emitting section from which the firstlight is emitted, and at least one side surface of the second activelayer included in the side surface of the laminated body is providedwith an emitting section from which the second light is emitted.

According to such a light emitting device as described above, it ispossible to simplify the layout of the wiring lines electricallyconnected to the electrodes when mounting.

The light emitting device according to the aspect of the invention maybe configured such that the first active layer has a first gain regionadapted to generate the first light in response to the injection of thecurrent, the first gain region includes a first gain portion having abelt-like shape extending from a first emitting section provided to afirst side surface of the first active layer to a first reflectingsection provided to a second side surface of the first active layer, asecond gain portion having a belt-like shape extending from the firstreflecting section to a second reflecting section provided to a thirdside surface of the first active layer, and a third gain portion havinga belt-like shape extending from the second reflecting section to asecond emitting section provided to the first side surface, the secondactive layer has a second gain region adapted to generate the secondlight in response to the injection of the current, the second gainregion includes a fourth gain portion having a belt-like shape extendingfrom a third emitting section provided to a fourth side surface of thesecond active layer to a third reflecting section provided to a fifthside surface of the second active layer, a fifth gain portion having abelt-like shape extending from the third reflecting section to a fourthreflecting section provided to a sixth side surface of the second activelayer, and a sixth gain portion having a belt-like shape extending fromthe fourth reflecting section to a fourth emitting section provided tothe fourth side surface, the first side surface and the fourth sidesurface constitute a part of the side surface of the laminated bodyhaving the normal line perpendicular to the stacking direction of thelaminated body, and the first light emitted from the first emittingsection, the first light emitted from the second emitting section, thesecond light emitted from the third emitting section, and the secondlight emitted from the fourth emitting section are emitted in the samedirection.

According to such a light emitting device as described above, thedistance between the first emitting section and the second emittingsection can be adjusted by the length of the second gain portion.Further, the distance between the third emitting section and the fourthemitting section can be adjusted by the length of the fourth gainportion.

The light emitting device according to the aspect of the invention maybe configured such that the first gain region and the second gain regioneach have a bracket shape when viewed from the stacking direction of thelaminated body.

According to such a light emitting device as described above, thedistance between the first emitting section and the second emittingsection of the first gain region can be adjusted. Further, the distancebetween the third emitting section and the fourth emitting section ofthe second gain region can be adjusted.

The light emitting device according to the aspect of the invention maybe configured such that a wavelength of the first light is no smallerthan 435 nm and no larger than 485 nm, and a wavelength of the secondlight is no smaller than 485 nm and no larger than 570 nm.

According to such a light emitting device as described above, it ispossible to set the first light to blue light, and the second light togreen light. Thus, it is possible to use the light emitting device asthe blue light source and the green light source of the projector.Therefore, the number of the light emitting devices can be reducedcompared to the case of using respective light emitting devices forthree light sources. Therefore, the number of optical systems such aslens arrays (microlens arrays) to which the light emitted from the lightsource is input can be reduced. As a result, the cost reduction can moresurely be achieved.

The light emitting device according to the aspect of the invention maybe configured such that the first gain region and the second gain regionfail to overlap each other when viewed from the stacking direction ofthe laminated body.

According to such a light emitting device as described above, the lightloss in the overlapping portion can be reduced. For example, when thefirst gain region and the second gain region overlap each other in theplan view, the light loss in the overlapping portion may be increased insome cases.

The light emitting device according to the aspect of the invention maybe configured such that the second gain portion of the first gain regionincludes a gap section where the second gain portion is divided, and thefourth gain portion of the second gain region is disposed so as to passthrough the gap section when viewed from the stacking direction of thelaminated body.

According to such a light emitting device as described above, it ispossible to simplify the layout of the wiring lines electricallyconnected to the electrodes when mounting.

The light emitting device according to the aspect of the invention maybe configured such that the first gain region is surrounded by thesecond gain region and the first side surface when viewed from thestacking direction of the laminated body.

According to such a light emitting device as described above, the lengthof the second gain region can be set to be greater than the length ofthe first gain region. For example, in the case in which the first lightgenerated in the first gain region is the blue light, and the secondlight generated in the second gain region is the green light, the lengthof the gain region of the green light with low gain can be increased tothereby improve the intensity and the emission efficiency of the greenlight. In the case of using such a light emitting device to theprojector, since the intensity and the emission efficiency of the greenlight having a high luminous sensitivity can be improved, a projectorwith higher luminous flux can be realized.

The light emitting device according to the aspect of the invention maybe configured such that the second electrode has a surface larger thanthe first gain region to cover the first gain region when viewed fromthe stacking direction of the laminated body, the third electrode has asurface larger than the second gain region to cover the second gainregion when viewed from the stacking direction of the laminated body,the first gain region is located below an end portion of the secondelectrode, the end portion being located near to the second gain region,and the second gain region is located below an end portion of the thirdelectrode, the end portion being located near to the first gain region.

According to such a light emitting device as described above, it ispossible to more surely decrease the distance between the first emittingsection and the third emitting section, and the distance between thesecond emitting section and the fourth emitting section. Thus, it ispossible to make the lights emitted from the first emitting section andthe third emitting section enter a single collecting lens, and make thelights emitted from the second emitting section and the fourth emittingsection enter another single collecting lens more reliably. Therefore,in the case of using the light emitting device as the light source ofthe projector, the number of microlenses can be decreased.

A projector according to another aspect of the invention includes thelight emitting device according to any one of the above aspects of theinvention, a light modulation device adapted to modulate the lightsemitted from the light emitting device in accordance with imageinformation to form an image, and a projection device adapted to projectthe image formed by the light modulation device.

According to such a projector as described above, the number of opticalsystems and the number of light valves can be decreased. Thus, the costreduction can be achieved.

A super-luminescent diode according to still another aspect of theinvention includes a substrate, a laminated body formed by stacking afirst cladding layer, a first active layer, a second cladding layer, athird cladding layer, a second active layer, and a fourth cladding layeron the substrate in this order, at least one first electrodeelectrically connected to the first cladding layer, a second electrodeelectrically connected to the second cladding layer and the thirdcladding layer, and a third electrode electrically connected to thefourth cladding layer, the first electrode, the second electrode, andthe third electrode are located on an opposite surface of the laminatedbody to the substrate, the first active layer generates first light inresponse to current injected using the first electrode and the secondelectrode, and the second active layer generates second light inresponse to current injected using the second electrode and the thirdelectrode.

According to such a super-luminescent diode as described above, it ispossible to simplify the layout of the wiring lines electricallyconnected to the electrodes when mounting.

A projector according to yet another aspect of the invention includesthe super-luminescent diode according to the aspect of the invention, alight modulation device adapted to modulate the lights emitted from thesuper-luminescent diode in accordance with image information to form animage, and a projection device adapted to project the image formed bythe light modulation device.

According to such a projector as described above, the number of opticalsystems and the number of light valves can be decreased. Thus, the costreduction can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a perspective view schematically showing a light emittingdevice according to an embodiment of the invention.

FIG. 2 is a plan view schematically showing the light emitting deviceaccording to the embodiment.

FIG. 3 is a cross-sectional view schematically showing the lightemitting device according to the embodiment.

FIG. 4 is a plan view schematically showing the light emitting deviceaccording to the embodiment.

FIG. 5 is a plan view schematically showing the light emitting deviceaccording to the embodiment.

FIG. 6 is a cross-sectional view schematically showing a manufacturingprocess of the light emitting device according to the embodiment.

FIG. 7 is a cross-sectional view schematically showing the manufacturingprocess of the light emitting device according to the embodiment.

FIG. 8 is a plan view schematically showing a light emitting deviceaccording to a first modified example of the embodiment.

FIG. 9 is a cross-sectional view schematically showing the lightemitting device according to the first modified example of theembodiment.

FIG. 10 is a plan view schematically showing a light emitting deviceaccording to a second modified example of the embodiment.

FIG. 11 is a cross-sectional perspective view schematically showing thelight emitting device according to the second modified example of theembodiment.

FIG. 12 is a plan view schematically showing a light emitting deviceaccording to a third modified example of the embodiment.

FIG. 13 is a plan view schematically showing a light source moduleaccording to the embodiment.

FIG. 14 is a cross-sectional view schematically showing a light sourcemodule according to the embodiment.

FIG. 15 is a cross-sectional view schematically showing the light sourcemodule according to the embodiment.

FIG. 16 is a perspective view schematically showing a projectoraccording to the embodiment.

FIG. 17 is a diagram schematically showing the projector according tothe embodiment.

FIG. 18 is a perspective view schematically showing the projectoraccording to the embodiment.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT

Hereinafter, a preferred embodiment of the invention will be explainedin detail with reference to the accompanying drawings. It should benoted that the embodiment described below does not unreasonably limitthe contents of the invention as set forth in the appended claims.Further, all of the constituents explained hereinafter are notnecessarily essential elements of the invention.

1. Light Emitting Device

Firstly, a light emitting device according to the present embodimentwill be explained with reference to the accompanying drawings. FIG. 1 isa perspective view schematically showing a light emitting device 100according to the present embodiment. FIG. 2 is a plan view schematicallyshowing the light emitting device 100 according to the presentembodiment. FIG. 3 is a cross-sectional view along the line III-IIIshown in FIG. 2, and schematically shows the light emitting device 100according to the present embodiment. FIG. 4 is a plan view schematicallyshowing the light emitting device 100 according to the presentembodiment. FIG. 5 is a plan view schematically showing the lightemitting device 100 according to the present embodiment. It should benoted that in FIG. 4, the cross-section including a first active layer106 of the light emitting device 100 is shown as a plan view, and inFIG. 5, the cross-section including a second active layer 112 of thelight emitting device 100 is shown as a plan view. Further, in FIGS. 1through 5, an X axis, a Y axis, and a Z axis are shown as three axesperpendicular to each other.

The case in which the light emitting device 100 is an SLD will beexplained below. Unlike the semiconductor laser, in the SLD, the laseroscillation can be prevented by suppressing formation of the resonatordue to edge reflection (the end surface reflection). Therefore, thespeckle noise can be reduced.

As shown in FIGS. 1 to 5, the light emitting device 100 includes asubstrate 102, a laminated body 130, first electrodes 120, a secondelectrode 122, and a third electrode 124. Further, the light emittingdevice 100 can include an insulating layer 116.

As the substrate 102, for example, an insulating substrate, asemiconductor substrate, or an electrically conductive substrate isused. More specifically, a sapphire substrate having an insulatingproperty can be used as the substrate 102.

The laminated body 130 is formed on the substrate 102. The laminatedbody 130 can have a structure obtained by stacking a first claddinglayer 104, a first active layer 106, a second cladding layer 108, athird cladding layer 110, a second active layer 112, and a fourthcladding layer 114 on the substrate 102 in this order. The firstcladding layer 104, the first active layer 106, the second claddinglayer 108, the third cladding layer 110, the second active layer 112,and the fourth cladding layer 114 are stacked in the Z-axis direction.

The laminated body 130 can have first portions 132, a second portion134, and a third portion 136. The first portions 132 are located betweenthe substrate 102 and the respective first electrodes 120, and areprovided with the first cladding layer 104. The second portion 134 islocated between the substrate 102 and the second electrode 122, and isprovided with the first cladding layer 104, the first active layer 106,the second cladding layer 108, and the third cladding layer 110. Thethird portion 136 is located between the substrate 102 and the thirdelectrode 124, and is provided with the first cladding layer 104, thefirst active layer 106, the second cladding layer 108, the thirdcladding layer 110, the second active layer 112, and the fourth claddinglayer 114.

In the example shown in FIG. 2, the planar shape (the shape viewed fromthe Z-axis direction) of the laminated body 130 is a rectangular shape.The laminated body 130 can have side surfaces 130 a, 130 b parallel tothe stacking direction (the Z-axis direction) (having a normal lineperpendicular to the stacking direction) of the laminated body.

The second portion 134 of the laminated body 130 is provided withopening sections 30, 32. In the example shown in FIGS. 1 and 2, theopening sections 30, 32 are also provided to the second electrode 122.The opening sections 30, 32 extend, for example, from the secondelectrode 122 to the first cladding layer 104.

The third portion 136 of the laminated body 130 is provided with openingsections 34, 36. In the example shown in FIGS. 1 and 2, the openingsections 34, 36 are also provided to the third electrode 124. Theopening sections 34, 36 extend, for example, from the third electrode124 to the third cladding layer 110.

The inside of the opening sections 30, 32, 34, and 36 can be hollowed,or filled with a reflecting film (the detail will be described later).The planar shape of the opening sections 30, 32, 34, and 36 is notparticularly limited, but is a triangular shape in the example shown inFIG. 2.

The first cladding layer 104 is formed on the substrate 102. As thefirst cladding layer 104, a GaN layer or an AlGaN layer of a firstconductivity type (e.g., an n type), for example, is used.

The first active layer 106 is formed on the first cladding layer 104.The first active layer 106 has a multiple quantum well (MQW) structurehaving, for example, three quantum well structures each composed of awell layer and a barrier layer. As the well layer, for example, an InGaNlayer is used. As the barrier layer, for example, a GaN layer, an InGaNlayer having the proportion of the In component lower than that in thewell layer, or an AlGaN layer having the proportion of the Al componentlower than that in the first cladding layer 104 is used.

As shown in FIG. 4, the first active layer 106 has a first side surface106 a, a second side surface 106 b, and a third side surface 106 c. Thefirst side surface 106 a constitutes a part of the side surface 130 a ofthe laminated body 130. In the example shown in FIG. 4, the first sidesurface 106 a is a surface of the first active layer 106, the surfacebeing located on the +X-axis direction side. The second side surface 106b defines one of the opening section 30. The third side surface 106 cdefines one of the opening section 32. The second side surface 106 b andthe third side surface 106 c are tilted with respect to the first sidesurface 106 a. The first side surface 106 a can be a cleaved surfaceformed by cleavage. The second side surface 106 b and the third sidesurface 106 c each can be an etched surface formed by etching.

Part of the first active layer 106 constitutes a first gain region 140.The first gain region 140 can generate first light in response toinjection current, and the first light can be guided in the first gainregion 140 while receiving a gain. The first gain region 140 is providedwith a first gain portion 142, a second gain portion 144, and a thirdgain portion 146.

The first gain portion 142 extends from the first side surface 106 a tothe second side surface 106 b in a plan view. When viewed from thestacking direction of the laminated body 130 (hereinafter also expressedas “in the plan view”), the first gain portion 142 has a predeterminedwidth, and is provided with a belt-like and linear longitudinal shapealong the extending direction of the first gain region 142. The firstgain portion 142 has a first end surface 151 provided to the connectionportion with the first side surface 106 a, and a second end surface 152provided to the connection portion with the second side surface 106 b.

It should be noted that the extending direction of the first gainportion 142 denotes, for example, the extending direction of a straightline passing through the center of the first end surface 151 and thecenter of the second end surface 152 in the plane view. Further, it canalso be the extending direction of a boundary line of the first gainportion 142 (with the portion except the first gain portion 142).

Similarly, also in other gain portions, the extending direction denotes,for example, the extending direction of a straight line passing throughthe centers of two end surfaces in the plan view. Further, the directionof the boundary line of the gain portion (with the portion except thegain portion) can also be adopted.

The first gain portion 142 is connected to the first side surface 106 awhile being tilted at an angle α1 with a perpendicular P1 of the firstside surface 106 a in the plan view. In other words, it can be said thatthe extending direction of the first gain portion 142 has an angle α1with the perpendicular P1. The angle α1 is an acute angle, and issmaller than the critical angle.

The first gain portion 142 is connected to the second side surface 106 bwhile being tilted at an angle α2 with a perpendicular P2 of the secondside surface 106 b in the plan view. In other words, it can be said thatthe extending direction of the first gain portion 142 has an angle α2with the perpendicular P2.

The second gain portion 144 extends from the second side surface 106 bto the third side surface 106 c in the plan view. In the plan view, thesecond gain portion 144 has a predetermined width, and is provided witha belt-like and linear longitudinal shape along the extending directionof the second gain portion 144. The second gain portion 144 has a thirdend surface 153 provided to the connection portion with the second sidesurface 106 b, and a fourth end surface 154 provided to the connectionportion with the third side surface 106 c. In the plan view, theextending direction of the second gain portion 144 is parallel to, forexample, the first side surface 106 a.

It should be noted that the sentence that “the extending direction ofthe second gain portion 144 is parallel to the first side surface 106 a”denotes that the tilt angle of the second gain portion 144 with respectto the first side surface 106 a is within ±1° in the plan view takingthe production tolerance into consideration.

The third end surface 153 of the second gain portion 144 overlaps thesecond end surface 152 of the first gain portion 142 on the second sidesurface 106 b. In the example shown in the drawings, the second endsurface 152 and the third end surface 153 completely overlap each otherin an overlapping plane 158.

The second gain portion 144 is connected to the second side surface 106b while being tilted at the angle α2 with the perpendicular P2 of thesecond side surface 106 b in the plan view. In other words, it can besaid that the extending direction of the second gain portion 144 has anangle α2 with the perpendicular P2. That is, the angle of the first gainportion 142 with respect to the perpendicular P2 and the angle of thesecond gain portion 144 with respect to the perpendicular P2 are equalto each other within the range of the production tolerance. The angle α2is, for example, an acute angle, and is equal to or larger than thecritical angle. Thus, the second side surface 106 b can totally reflectthe light generated in the first gain region 140.

It should be noted that the sentence that “an angle θ1 and an angle θ2are equal to each other within the production tolerance” denotes thatthe difference between the angles is within, for example, ±2° taking theproduction tolerance such as etching into consideration.

The second gain portion 144 is connected to the third side surface 106 cwhile being tilted at an angle α3 with a perpendicular P3 of the thirdside surface 106 c in the plan view. In other words, it can be said thatthe extending direction of the second gain portion 144 has an angle α3with the perpendicular P3.

The length of the second gain portion 144 in the extending direction canbe larger than the length of the first gain portion 142 in the extendingdirection and the length of the third gain portion 146 in the extendingdirection. The length of the second gain portion 144 in the extendingdirection can also be equal to or greater than the sum of the length ofthe first gain portion 142 in the extending direction and the length ofthe third gain portion 146 in the extending direction. It should benoted that “the length of the second gain portion 144 in the extendingdirection” can also be said to be the distance between the center of thethird end surface 153 and the center of the fourth end surface 154.Similarly, also in other gain portions, it can be said that the lengthin the extending direction is the distance between the centers of thetwo end surfaces.

The third gain portion 146 extends from the third side surface 106 c tothe first side surface 106 a in the plan view. In the plan view, thethird gain portion 146 has, for example, a predetermined width, and isprovided with a belt-like and linear longitudinal shape along theextending direction of the third gain portion 146. The third gainportion 146 has a fifth end surface 155 provided to the connectionportion with the third side surface 106 c, and a sixth end surface 156provided to the connection portion with the first side surface 106 a.

The fifth end surface 155 of the third gain portion 146 overlaps thefourth end surface 154 of the second gain portion 144 on the third sidesurface 106 c. In the example shown in the drawings, the fourth endsurface 154 and the fifth end surface 155 completely overlap each otherin an overlapping plane 159.

The third gain portion 146 is connected to the third side surface 106 cwhile being tilted at an angle α3 with the perpendicular P3 of the thirdside surface 106 c in the plan view. In other words, it can be said thatthe extending direction of the third gain portion 146 has an angle α3with the perpendicular P3. That is, the angle of the second gain portion144 with respect to the perpendicular P3 and the angle of the third gainportion 146 with respect to the perpendicular P3 are equal to each otherwithin the range of the production tolerance. The angle α3 is, forexample, an acute angle, and is equal to or larger than the criticalangle. Thus, the third side surface 106 c can totally reflect the lightgenerated in the first gain region 140.

The third gain portion 146 is connected to the first side surface 106 awhile being tilted at an angle α1 with the perpendicular P1 in the planview. In other words, it can be said that the longitudinal direction ofthe third gain portion 146 has an angle α1 with the perpendicular P1.That is, the first gain portion 142 and the third gain portion 146 areconnected to the first side surface 106 a in the same direction, and areparallel to each other. More specifically, the extending direction ofthe first gain portion 142 and the extending direction of the third gainportion 146 are parallel to each other. Thus, the first light 20 emittedfrom the first end surface 151 and the first light 20 emitted from thesixth end surface 156 can be emitted in the same direction.

As described above, by setting the angles α2, α3 to be equal to orlarger than the critical angle, and setting the angle α1 to be smallerthan the critical angle, the reflectance of the first side surface 106 acan be made lower than the reflectance of the second side surface 106 band the reflectance of the third side surface 106 c. Thus, it ispossible for the first end surface 151 provided to the first sidesurface 106 a to become a first emitting section (a first emittingsection 151) for emitting the light generated in the first gain region140. It is possible for the sixth end surface 156 provided to the firstside surface 106 a to become a second emitting section (a secondemitting section 156) for emitting the light generated in the first gainregion 140. It is possible for the overlapping plane 158 between the endsurfaces 152, 153 provided to the second side surface 106 b to become afirst reflecting section (a first reflecting section 158) for reflectingthe light generated in the first gain region 140. It is possible for theoverlapping plane 159 between the end surfaces 154, 155 provided to thethird side surface 106 c to become a second reflecting section (a secondreflecting section 159) for reflecting the light generated in the firstgain region 140.

In other words, the first gain portion 142 extends from the firstemitting section 151 to the first reflecting section 158, the secondgain portion 144 extends from the first reflecting section 158 to thesecond reflecting section 159, the third gain portion 146 extends fromthe second reflecting section 159 to the second emitting section 156.Therefore, it can be said that the first gain region 140 has a bracketshape (a U shape with corners) in the plan view.

It should be noted that, although the surfaces of the emitting sections151, 156 and the reflecting sections 158, 159 are exposed in the exampleshown in the drawing, it is also possible for the first side surface 106a (the emitting sections 151, 156) to be covered by an antireflectionfilm, and for the second side surface 106 b and the third side surface106 c (the reflecting sections 158, 159) to be covered by a reflectingfilm. Thus, even under the condition of the incident angle, therefractive index, and so on with which the light generated in the firstgain region 140 fails to be totally reflected by the reflecting sections158, 159, it is possible to make the reflectance of the first sidesurface 106 a lower than the reflectance of the second side surface 106b and the reflectance of the third side surface 106 c in the wavelengthband of the light generated in the first gain region 140. Further, bycovering the first side surface 106 a with the antireflection film, itcan be possible to suppress the light generated in the first gain region140 to be multiply reflected directly between the first end surface 151and the sixth end surface 156. As a result, since it can be prevented toconstitute the direct resonator, the laser oscillation of the lightgenerated in the first gain region 140 can be suppressed.

As the reflecting film and the antireflection film, for example, an SiO₂layer, a Ta₂O₅ layer, an Al₂O₃ layer, a TiN layer, a TiO₂ layer, an SiONlayer, an SiN layer, and a multilayer film of these layers can be used.Further, it is also possible to form a distributed Bragg reflector (DBR)on each of the side surfaces 106 b, 106 c by etching to thereby obtain ahigh reflectance.

Further, the angle α1 can be an angle larger than 0°. Thus, it ispossible to prevent the light generated in the first gain region 140from being multiply reflected directly between the first end surface 151and the sixth end surface 156. As a result, since it can be prevented toconstitute the direct resonator, the laser oscillation of the lightgenerated in the first gain region 140 can be suppressed or prevented.

It should be noted that the angle α1 can be equal to 0° although notshown in the drawings. In other words, the extending direction of thegain portions 142, 146 can be parallel to the perpendicular P1 in theplan view. As described above, even in such a configuration, by coveringthe first side surface 106 a with the antireflection film, it ispossible to suppress the light generated in the first gain region 140 tobe multiply reflected directly between the first end surface 151 and thesixth end surface 156.

As shown in FIGS. 1 and 3, the second cladding layer 108 is formed onthe first active layer 106. As the second cladding layer 108, a GaNlayer or an AlGaN layer of a second conductivity type (e.g., a p type),for example, is used.

A pin diode is constituted by, for example, the p-type second claddinglayer 108, the first active layer 106 with no impurity doped, and then-type first cladding layer 104. Each of the first cladding layer 104and the second cladding layer 108 is a layer having a forbidden-bandwidth larger than that of the first active layer 106 and a refractiveindex smaller than that of the first active layer 106. The first activelayer 106 has a function of generating the first light in response tothe injection current by the first electrodes 120 and the secondelectrode 122 and a function of guiding the first light while amplifyingthe first light. The first cladding layer 104 and the second claddinglayer 108 sandwiching the first active layer 106 therebetween have afunction of confining the injected carriers (electrons and holes) andthe light therein (suppressing the leakage of carriers and light).

In the light emitting device 100, when applying a forward bias voltageof the pin diode between the first electrodes 120 and the secondelectrode 122 (injecting electrical current), the first gain region 140is generated in the first active layer 106, and there occursrecombination of electrons and holes in the first gain region 140. Therecombination generates light. The stimulated emission occurs in achained manner taking the light thus generated as a starting point, andthe light intensity is amplified inside the first gain region 140 towhich electrical current is injected.

For example, as shown in FIG. 4, the first light 10 generated in thefirst gain portion 142 and proceeding toward the second side surface 106b is amplified in the first gain portion 142, and is then reflected bythe first reflecting section 158, and then proceeds through the secondgain portion 144 toward the third side surface 106 c. Then, the firstlight 10 is further reflected by the second reflecting section 159, thenproceeds through the third gain portion 146, and is then emitted fromthe sixth end surface 156 as the first light 20. On this occasion, thelight intensity is also amplified in the gain portions 144, 146.Similarly, the first light generated in the third gain portion 146 andproceeding toward the third side surface 106 c is amplified in the thirdgain portion 146, and is then reflected by the second reflecting section159, and then proceeds through the second gain portion 144 toward thesecond side surface 106 b. Then, the first light is further reflected bythe first reflecting section 158, then proceeds through the first gainportion 142, and is then emitted from the first end surface 151 as thefirst light 20. On this occasion, the light intensity is also amplifiedin the gain portions 142, 144.

It should be noted that some of the light generated in the first gainportion 142 is emitted directly from the first end surface 151 as thefirst light 20. Similarly, some of the light generated in the third gainportion 146 is emitted directly from the sixth end surface 156 as thefirst light 20. These lights are also amplified in the respective gainportions 142, 146 in a similar manner.

As shown in FIGS. 1 and 3, the third cladding layer 110 is formed on thesecond cladding layer 108. As the third cladding layer 110, a GaN layeror an AlGaN layer of the second conductivity type (e.g., the p type),for example, is used.

The second active layer 112 is formed on the third cladding layer 110.The second active layer 112 has a multiple quantum well (MQW) structurehaving, for example, three quantum well structures each composed of awell layer and a barrier layer. As the well layer, for example, an InGaNlayer is used. As the barrier layer, for example, a GaN layer, an InGaNlayer having the proportion of the In component lower than that in thewell layer, or an AlGaN layer having the proportion of the Al componentlower than that in the first cladding layer 104 is used. It should benoted that it is possible that the In component of the InGaN layerconstituting the well layer of the first active layer 106 and the Incomponent of the InGaN layer constituting the well layer of the secondactive layer 112 are different from each other to thereby make thewavelength of the first light generated in the first active layer 106and the wavelength of the second light generated in the second activelayer 112 different from each other.

As shown in FIG. 5, the second active layer 112 has a fourth sidesurface 112 a, a fifth side surface 112 b, and a sixth side surface 112c. The fourth side surface 112 a constitutes a part of the side surface130 a of the laminated body 130. In the example shown in FIG. 5, thefourth side surface 112 a is a surface of the second active layer 112,the surface being located on the +X-axis direction side. The fifth sidesurface 112 b defines one of the surfaces of the opening section 34. Thesixth side surface 112 c defines one of the surfaces of the openingsection 36. The fifth side surface 112 b and the sixth side surface 112c are tilted with respect to the fourth side surface 112 a. The fourthside surface 112 a can be a cleaved surface formed by cleavage. Thefifth side surface 112 b and the sixth side surface 112 c each can be anetched surface formed by etching.

Part of the second active layer 112 constitutes a second gain region160. The second gain region 160 can generate second light in response toinjection current, and the second light can be guided in the second gainregion 160 while receiving a gain. The second gain region 160 isprovided with a fourth gain portion 162, a fifth gain portion 164, and asixth gain portion 166.

The fourth gain portion 162 extends from the fourth side surface 112 ato the fifth side surface 112 b in the plan view. In the plan view, thefourth gain portion 162 has a predetermined width, and is provided witha belt-like and linear longitudinal shape along the extending directionof the fourth gain portion 162. The fourth gain portion 162 has a firstend surface 171 provided to the connection portion with the fourth sidesurface 112 a, and a second end surface 172 provided to the connectionportion with the fifth side surface 112 b.

The fourth gain portion 162 is connected to the fourth side surface 112a while being tilted at an angle β1 with a perpendicular Q1 of thefourth side surface 112 a in the plan view. In other words, it can besaid that the extending direction of the fourth gain portion 162 has anangle β1 with the perpendicular Q1. The angle β1 is an acute angle, andis smaller than the critical angle.

The fourth gain portion 162 is connected to the fifth side surface 112 bwhile being tilted at an angle β2 with a perpendicular Q2 of the fifthside surface 112 b in the plan view. In other words, it can be said thatthe extending direction of the fourth gain portion 162 has an angle β2with the perpendicular Q2.

The fifth gain portion 164 extends from the fifth side surface 112 b tothe sixth side surface 112 c in the plan view. In the plan view, thefifth gain portion 164 has a predetermined width, and is provided with abelt-like and linear longitudinal shape along the extending direction ofthe fifth gain portion 164. The fifth gain portion 164 has a third endsurface 173 provided to the connection portion with the fifth sidesurface 112 b, and a fourth end surface 174 provided to the connectionportion with the sixth side surface 112 c. In the plan view, theextending direction of the fifth gain portion 164 is parallel to, forexample, the fourth side surface 112 a.

It should be noted that the sentence that “the extending direction ofthe fifth gain portion 164 is parallel to the fourth side surface 112 a”denotes that the tilt angle of the fifth gain portion 164 with respectto the fourth side surface 112 a is within ±1° in the plan view takingthe production tolerance into consideration.

The third end surface 173 of the fifth gain portion 164 overlaps thesecond end surface 172 of the fourth gain portion 162 on the fifth sidesurface 112 b. In the example shown in the drawings, the second endsurface 172 and the third end surface 173 completely overlap each otherin an overlapping plane 178.

The fifth gain portion 164 is connected to the fifth side surface 112 bwhile being tilted at an angle β2 with the perpendicular Q2 of the fifthside surface 112 b in the plan view. In other words, it can be said thatthe extending direction of the fifth gain portion 164 has an angle β2with the perpendicular Q2. That is, the angle of the fourth gain portion162 with respect to the perpendicular Q2 and the angle of the fifth gainportion 164 with respect to the perpendicular Q2 are equal to each otherwithin the range of the production tolerance. The angle β2 is, forexample, an acute angle, and is equal to or larger than the criticalangle. Thus, the fifth side surface 112 b can totally reflect the lightgenerated in the second gain region 160.

The fifth gain portion 164 is connected to the sixth side surface 112 cwhile being tilted at an angle β3 with a perpendicular Q3 of the sixthside surface 112 c in the plan view. In other words, it can be said thatthe extending direction of the fifth gain portion 164 has an angle β3with the perpendicular Q3.

The length of the fifth gain portion 164 in the extending direction canbe larger than the length of the fourth gain portion 162 in theextending direction, and the length of the sixth gain portion 166 in theextending direction. The length of the fifth gain portion 164 in theextending direction can also be equal to or greater than the sum of thelength of the fourth gain portion 162 in the extending direction and thelength of the sixth gain portion 166 in the extending direction.

The sixth gain portion 166 extends from the sixth side surface 112 c tothe fourth side surface 112 a in the plan view. In the plan view, thesixth gain portion 166 has, for example, a predetermined width, and isprovided with a belt-like and linear longitudinal shape along theextending direction of the sixth gain portion 166. The sixth gainportion 166 has a fifth end surface 175 provided to the connectionportion with the sixth side surface 112 c, and a sixth end surface 176provided to the connection portion with the fourth side surface 112 a.

The fifth end surface 175 of the sixth gain portion 166 overlaps thefourth end surface 174 of the fifth gain portion 164 on the sixth sidesurface 112 c. In the example shown in the drawings, the fourth endsurface 174 and the fifth end surface 175 completely overlap each otherin an overlapping plane 179.

The sixth gain portion 166 is connected to the sixth side surface 112 cwhile being tilted at an angle β3 with the perpendicular Q3 of the sixthside surface 112 c in the plan view. In other words, it can be said thatthe extending direction of the sixth gain portion 166 has an angle β3with the perpendicular Q3. That is, the angle of the fifth gain portion164 with respect to the perpendicular Q3 and the angle of the sixth gainportion 166 with respect to the perpendicular Q3 are equal to each otherwithin the range of the production tolerance. The angle β3 is, forexample, an acute angle, and is equal to or larger than the criticalangle. Thus, the sixth side surface 112 c can totally reflect the lightgenerated in the second gain region 160.

The sixth gain portion 166 is connected to the fourth side surface 112 awhile being tilted at an angle β1 with the perpendicular Q1 in the planview. In other words, it can be said that the longitudinal direction ofthe sixth gain portion 166 has an angle β1 with the perpendicular Q1. Inother words, the fourth gain portion 162 and the sixth gain portion 166are connected to the fourth side surface 112 a in the same direction,and are parallel to each other. More specifically, the extendingdirection of the fourth gain portion 162 and the extending direction ofthe sixth gain portion 166 are parallel to each other. Thus, the light22 emitted from the first end surface 171 and the light 22 emitted fromthe sixth end surface 176 can be emitted in the same direction.

As described above, by setting the angles β2, β3 to be equal to orlarger than the critical angle, and setting the angle β1 to be smallerthan the critical angle, the reflectance of the fourth side surface 112a can be made lower than the reflectance of the fifth side surface 112 band the reflectance of the sixth side surface 112 c. Thus, it ispossible for the first end surface 171 provided to the fourth sidesurface 112 a to become a third emitting section (a third emittingsection 171) for emitting the light generated in the second gain region160. It is possible for the sixth end surface 176 provided to the fourthside surface 112 a to become a fourth emitting section (a fourthemitting section 176) for emitting the light generated in the secondgain region 160. It is possible for the overlapping plane 178 betweenthe end surfaces 172, 173 provided to the fifth side surface 112 b tobecome a third reflecting section (a third reflecting section 178) forreflecting the light generated in the second gain region 160. It ispossible for the overlapping plane 179 between the end surfaces 174, 175provided to the sixth side surface 112 c to become a fourth reflectingsection (a fourth reflecting section 179) for reflecting the lightgenerated in the second gain region 160.

In other words, the fourth gain portion 162 extends from the thirdemitting section 171 to the third reflecting section 178, the fifth gainportion 164 extends from the third reflecting section 178 to the fourthreflecting section 179, the sixth gain portion 166 extends from thefourth reflecting section 179 to the fourth emitting section 176.Therefore, it can be said that the second gain region 160 has a bracketshape (a U shape with corners) in the plan view.

It should be noted that the emitting sections 171, 176 can be covered bythe antireflection film similarly to the emitting sections 151, 156described above. Further, the reflecting sections 178, 179 can becovered by the reflecting film similarly to the reflecting sections 158,159 described above. Thus, even under the condition of the incidentangle, the refractive index, and so on with which the light generated inthe second gain region 160 fails to be totally reflected by thereflecting sections 178, 179, it is possible to make the reflectance ofthe fourth side surface 112 a lower than the reflectance of the fifthside surface 112 b and the reflectance of the sixth side surface 112 cin the wavelength band of the light generated in the second gain region160. Further, by covering the fourth side surface 112 a with theantireflection film, it can be possible to suppress the light generatedin the second gain region 160 to be multiply reflected directly betweenthe first end surface 171 and the sixth end surface 176. As a result,since it can be prevented to constitute the direct resonator, the laseroscillation of the light generated in the second gain region 160 can besuppressed.

Further, the angle β1 can be an angle larger than 0°. Thus, it ispossible to prevent the light generated in the second gain region 160from being multiply reflected directly between the first end surface 171and the sixth end surface 176. As a result, since it can be prevented toconstitute the direct resonator, the laser oscillation of the lightgenerated in the second gain region 160 can be suppressed or prevented.

It should be noted that the angle β1 can be equal to 0° although notshown in the drawings. In other words, the extending directions of thegain portions 162, 166 can be parallel to the perpendicular Q1 in theplan view. As described above, even in such a configuration, by coveringthe fourth side surface 112 a with the antireflection film, it ispossible to suppress the light generated in the second gain region 160to be multiply reflected directly between the first end surface 171 andthe sixth end surface 176.

As shown in FIGS. 1 and 3, the fourth cladding layer 114 is formed onthe second active layer 112. As the fourth cladding layer 114, a GaNlayer or an AlGaN layer of the first conductivity type (e.g., the ntype), for example, is used.

A pin diode is constituted, for example, by the n-type fourth claddinglayer 114, the second active layer 112 with no impurity doped, and thep-type third cladding layer 110. Each of the third cladding layer 110and the fourth cladding layer 114 is a layer having a forbidden-bandwidth larger than that of the second active layer 112 and a refractiveindex smaller than that of the second active layer 112. The secondactive layer 112 has a function of generating the second light inresponse to the injection current by the second electrode 122 and thethird electrode 124 and a function of guiding the second light whileamplifying the second light. The third cladding layer 110 and the fourthcladding layer 114 sandwiching the second active layer 112 therebetweenhave a function of confine the injected carriers (electrons and holes)and the light therein (suppressing the leakage of carriers and light).

In the light emitting device 100, when applying a forward bias voltageof the pin diode between the second electrode 122 and the thirdelectrode 124 (injecting electrical current), the second gain region 160is generated in the second active layer 112, and there occursrecombination of electrons and holes in the second gain region 160. Therecombination generates light. The stimulated emission occurs in achained manner taking the light thus generated as a starting point, andthe light intensity is amplified inside the second gain region 160 towhich electrical current is injected.

For example, as shown in FIG. 5, the second light 12 generated in thefourth gain portion 162 and proceeding toward the fifth side surface 112b is amplified in the fourth gain portion 162, and is then reflected bythe third reflecting section 178, and then proceeds through the fifthgain portion 164 toward the sixth side surface 112 c. Then, the secondlight 12 is further reflected by the fourth reflecting section 179, thenproceeds through the sixth gain portion 166, and is then emitted fromthe sixth end surface 176 as the second light 22. On this occasion, thelight intensity is also amplified in the gain portions 164, 166.Similarly, the second light generated in the sixth gain portion 166 andproceeding toward the sixth side surface 112 c is amplified in the sixthgain portion 166, and is then reflected by the fourth reflecting section179, and then proceeds through the fifth gain portion 164 toward thefifth side surface 112 b. Then, the second light is further reflected bythe third reflecting section 178, then proceeds through the fourth gainportion 162, and is then emitted from the first end surface 171 as thesecond light 22. On this occasion, the light intensity is also amplifiedin the gain portions 162, 164.

It should be noted that some of the light generated in the fourth gainportion 162 is emitted directly from the first end surface 171 as thesecond light 22. Similarly, some of the light generated in the sixthgain portion 166 is emitted directly from the sixth end surface 176 asthe second light 22. These lights are also amplified in the respectivegain portions 162, 166 in a similar manner.

The wavelength of the first light generated in the first active layer106 is, for example, no smaller than 435 nm and no larger than 485 nm.In this case, the first light is blue light. The wavelength of thesecond light generated in the second active layer 112 is, for example,no smaller than 485 nm and no larger than 570 nm. In this case, thesecond light is green light.

It should be noted that the wavelength of the first light and thewavelength of the second light can be equal to each other. For example,the wavelength of the first light and the wavelength of the second lightare no smaller than 610 nm and no larger than 750 nm, and the firstlight and the second light can be red light. In this case, the activelayers 106, 112 can have a multiple quantum well (MQW) structure having,for example, three quantum well structures each composed of an InGaPwell layer and an InGaAlP barrier layer.

The first gain region 140 and the second gain region 160 do not overlapeach other in the plan view as shown in FIG. 2. In the example shown inFIG. 2, the first gain region 140 is surrounded by the second gainregion 160 and the first side surface 106 a of the first active layer106 in the plan view. The first emitting section 151 and the secondemitting section 156 of the first gain region 140 are located betweenthe third emitting section 171 and the fourth emitting section 176 ofthe second gain region 160. In the plan view, the distance D1 betweenthe center of the first emitting section 151 and the center of the thirdemitting section 171 is, for example, about 40 μm. Similarly, in theplan view, the distance D2 between the center of the second emittingsection 156 and the center of the fourth emitting section 176 is, forexample, about 40 μm.

The first light 20 emitted from the first emitting section 151, thefirst light 20 emitted from the second emitting section 156, the secondlight 22 emitted from the third emitting section 171, and the secondlight 22 emitted from the fourth emitting section 176 can be emitted inthe same direction. In the light emitting device 100, it is possible toadjust the angle α1 (see FIG. 4) and the angle β1 (see FIG. 5) so thatthe first light 20 and the second light 22 are emitted in the samedirection.

As shown in FIGS. 1 and 3, the insulating layer 116 is formed so as tocover the upper surface and the side surfaces of the laminated body 130.As shown in FIG. 1, the insulating layer 116 is formed avoiding the sidesurface 130 a of the laminated body 130. As the insulating layer 116,for example, an SiN layer or an SiON layer is used.

As shown in FIG. 3, the insulating layer 116 is provided with openings116 a, 116 b, and 116 c. The opening 116 a is located at the firstportions 132 of the laminated body 130. The opening 116 b is located atthe second portion 134 of the laminated body 130. The opening 116 c islocated at the third portion 136 of the laminated body 130.

The planar shape of the opening 116 b is the same as, for example, theplanar shape of the first gain region 140. The current channel betweenthe electrodes 120, 122 is determined in accordance with, for example,the planar shape of the opening 116 b, and as a result, the planar shapeof the first gain region 140 is determined. Further, the planar shape ofthe opening 116 c is the same as, for example, the planar shape of thesecond gain region 160. The current channel between the electrodes 122,124 is determined in accordance with, for example, the planar shape ofthe opening 116 c, and as a result, the planar shape of the second gainregion 160 is determined.

The first electrodes 120 are electrically connected to the firstcladding layer 104. The first electrodes 120 are located on the surfaceof the laminated body 130 on the opposite side to the substrate 102side. In the example shown in FIG. 3, the first electrodes 120 arelocated on the upper surfaces 132 a of the first portions 132 of thelaminated body 130. Since the opening 116 a is disposed, for example,the upper surface 132 a has a portion exposed in the laminated body 130.As shown in FIG. 3, each of the first electrodes 120 can have a portionhaving contact with the upper surface 132 a, and a portion havingcontact with the insulating layer 116 formed on the upper surface 132 a.

It should be noted that, although the upper surface 132 a is formed ofthe first cladding layer 104 in the example shown in the drawing, theupper surface 132 a can be formed of a first contact layer (not shown)disposed between the first cladding layer 104 and each of the firstelectrodes 120. The first contact layer can have ohmic contact with eachof the first electrodes 120.

As shown in FIGS. 1 and 2, the two first electrodes 120 are disposed,and as shown in FIG. 2, the second electrode 122 and the third electrode124 are disposed between the two first electrodes 120 in the plan view.The planar shape of each of the first electrodes 120 is not particularlylimited, but is a parallelogram shape in the example shown in FIG. 2.The width (the size in the Y-axis direction) of each of the firstelectrodes 120 is, for example, in a range of about 100 μm through 200μm.

The first electrodes 120 are each one of the electrodes for injectingthe current into the first active layer 106. As the first electrode 120,there can be used, for example, what is obtained by stacking a Ti layer,an Al layer, and an Au layer in this order from the laminated body 130side.

The second electrode 122 is electrically connected to the secondcladding layer 108 and the third cladding layer 110. The secondelectrode 122 is located on the surface of the laminated body 130 on theopposite side to the substrate 102 side. In the example shown in FIG. 3,the second electrode 122 is located on the upper surface 134 a of thesecond portion 134 of the laminated body 130. Since the opening 116 b isdisposed, for example, the upper surface 134 a has a portion exposed inthe laminated body 130. As shown in FIG. 3, the second electrode 122 canhave a portion having contact with the upper surface 134 a, and aportion having contact with the insulating layer 116 formed on the uppersurface 134 a.

It should be noted that, although the upper surface 134 a is formed ofthe second cladding layer 108 and the third cladding layer 110 in theexample shown in the drawings, the upper layer 134 a can be formed of asecond contact layer (not shown) disposed between the cladding layers108, 110 and the second electrode 122. The second contact layer can haveohmic contact with the second electrode 122.

As shown in FIG. 2, the second electrode 122 has a surface 122 a largerthan the first gain region 140 to thereby cover the first gain region140 in the plan view. The surface 122 a is the upper surface of thesecond electrode 122. As shown in FIG. 3, the first gain region 140 islocated below an end portion 123 of the second electrode 122, the endportion 123 being located near to the second gain region 160 side.Specifically, as shown in FIG. 2, the first gain region 140 overlaps theend portion 123 of the second electrode 122 located near to the secondgain region 160 side in the plan view.

The second electrode 122 covers the first gain region 140 along thefirst gain region 140 in the plan view. The width (the size in theY-axis direction of the portions disposed along the gain portions 142,146, and the size in the X-axis direction of the portion disposed alongthe gain portion 144) of the second electrode 122 is, for example, in arange of about 100 μm through 200 μm. The second electrode 122 isdisposed so as to be surrounded by the third electrode 124 and the sidesurface 130 a of the laminated body 130 in the plan view.

The second electrode 122 is the other of the electrodes for injectingcurrent into the first active layer 106. Further, the second electrode122 is one of the electrodes for injecting current into the secondactive layer 112. As the second electrode 122, there can be used, forexample, what is obtained by stacking an Ni layer, a Pd layer, and an Aulayer in this order from the laminated body 130 side.

The third electrode 124 is electrically connected to the fourth claddinglayer 114. The third electrode 124 is located on the surface of thelaminated body 130 on the opposite side to the substrate 102 side. Inthe example shown in FIG. 3, the third electrode 124 is located on theupper surface 136 a of the third portion 136 of the laminated body 130.Since the opening 116 c is disposed, for example, the upper surface 136a has a portion exposed in the laminated body 130. As shown in FIG. 3,the third electrode 124 can have a portion having contact with the uppersurface 136 a, and a portion having contact with the insulating layer116 formed on the upper surface 136 a.

It should be noted that although the upper surface 136 a is formed ofthe fourth cladding layer 114 in the example shown in the drawings, theupper surface 136 a can be formed of a third contact layer (not shown)disposed between the fourth cladding layer 114 and the third electrode124. The third contact layer can have ohmic contact with the thirdelectrode 124.

As shown in FIG. 2, the third electrode 124 has a surface 124 a largerthan the second gain region 160 to thereby cover the second gain region160 in the plan view. The surface 124 a is the upper surface of thethird electrode 124. As shown in FIG. 3, the second gain region 160 islocated below an end portion 125 of the third electrode 124, the endportion 125 being located near to the first gain region 140 side.Specifically, as shown in FIG. 2, the second gain region 160 overlapsthe end portion 125 of the third electrode 124 located near to the firstgain region 140 side in the plan view.

The third electrode 124 covers the second gain region 160 along thesecond gain region 160 in the plan view. The width (the size in theY-axis direction of the portions disposed along the gain portions 162,166, the size in the X-axis of the portion disposed along the gainportion 164) of the third electrode 124 is, for example, in a range ofabout 100 μm through 200 μm.

The third electrode 124 is the other of the electrodes for injectingcurrent into the second active layer 112. As the third electrode 124,there can be used, for example, what is obtained by stacking a Ti layer,an Al layer, and an Au layer in this order from the laminated body 130side.

As shown in FIGS. 2 and 3, the center in the width direction of thesecond electrode 122 and the center in the width direction of theopening 116 b and the first gain region 140 can be shifted from eachother when viewed from the stacking direction of the laminated body 130.Similarly, the center in the width direction of the third electrode 124and the center in the width direction of the opening 116 c and thesecond gain region 160 can be shifted from each other.

The light emitting device 100 according to the present embodiment can beapplied to the light source for a projector, a monitor display, anillumination device, and a measuring device, for example.

The light emitting device 100 according to the present embodiment has,for example, the following features.

According to the light emitting device 100, the first electrodes 120,the second electrode 122, and the third electrode 124 are located on thesurface of the laminated body 130 on the opposite side to the substrate102 side. In other words, in the light emitting device 100, theelectrodes 120, 122, and 124 are formed on one side of the laminatedbody 130. Therefore, it is possible to simplify the layout of the wiringlines electrically connected to the electrodes 120, 122, and 124 whenmounting the light emitting device 100. More specifically, according tothe light emitting device 100, it is possible to dispose a mountingboard provided with the wiring lines on one side of the laminated body130, and mount the light emitting device 100 on the mounting board sothat the wiring lines and the electrodes 120, 122, and 124 areelectrically connected to each other.

Further, in the light emitting device 100, since the electrodes 120,122, and 124 are formed on one side of the laminated body 130, freedomflexibility of selecting the substrate material can be improved.Although which is limited to the substrate having electricalconductivity such as a GaN substrate or a silicon (111) substrate in thecase of the light emitting device having the electrodes disposed on bothsides of the substrate, according to the light emitting device 100, forexample, an insulating substrate such as a sapphire substrate can beused as the substrate 102.

Further, in the light emitting device 100, the first active layer 106and the second active layer 112 are formed on the same substrate 102.The first side surface 106 a of the first active layer 106 and thefourth side surface 112 a of the second active layer 112 are included inthe side surface 130 a of the laminated body 130. Therefore, it ispossible to reduce the distance D1 between the first emitting section151 disposed on the first side surface 106 a and the third emittingsection 171 disposed on the fourth side surface 112 a. Similarly, it ispossible to reduce the distance D2 between the second emitting section156 disposed on the first side surface 106 a and the fourth emittingsection 176 disposed on the fourth side surface 112 a. Thus, it ispossible to make the lights 20, 22 respectively emitted from theemitting sections 151, 171 enter a single collecting lens (a microlens).Similarly, it is possible to make the lights 20, 22 respectively emittedfrom the emitting sections 156, 176 enter a single collecting lens.Therefore, according to the light emitting device 100, in the case ofusing the light emitting device 100 as the light source of theprojector, the number of the collecting lenses can be reduced to therebyachieve the cost reduction.

As described above, according to the light emitting device 100, it ispossible to achieve simple layout of the wiring lines to be electricallyconnected to the electrodes in installation and improve the flexibilityof selecting the substrate material while achieving the cost reduction.

According to the light emitting device 100, the first gain region 140 isprovided with the first gain portion 142 having the first emittingsection 151, the third gain portion 146 having the second emittingsection 156, and the second gain portion 144 connected to the first gainportion 142 and the third gain portion 146. The second gain region 160is provided with the fourth gain portion 162 having the third emittingsection 171, the sixth gain portion 166 having the fourth emittingsection 176, and the fifth gain portion 164 connected to the fourth gainportion 162 and the sixth gain portion 166. Therefore, the distancebetween the emitting sections 151, 156 can be adjusted using the secondgain portion 144. Further, the distance between the emitting sections171, 176 can be adjusted using the fifth gain portion 164. Thus, in thelight emitting device 100, in the case of using the light emittingdevice 100 as the light source of the projector, it is possible toeasily adjust the distance between the emitting sections 151, 156 andthe distance between the emitting sections 171, 176 in accordance with,for example, the size of the collecting lens or the interval of lensarray (microlens array).

According to the light emitting device 100, it is possible to set thewavelength of the first light to a value no smaller than 435 nm and nolarger than 485 nm, and the wavelength of the second light to be nosmaller than 485 nm and no larger than 570 nm. In other words, it ispossible to set the first light to blue light, and the second light togreen light. Thus, it is possible to use the light emitting device 100as the blue light source and the green light source of the projector.Therefore, the number of the light emitting devices can be reducedcompared to the case of using respective light emitting devices forthree light sources. Therefore, the number of lens arrays (microlensarrays) to which the light emitted from the light source is input can bereduced. As a result, the cost reduction can more surely be achieved.

According to the light emitting device 100, the first gain region 140and the second gain region 160 do not overlap each other in the planview. Therefore, in the light emitting device 100, the light loss in theoverlapping portion can be reduced. For example, when the first gainregion and the second gain region overlap each other in the plan view,the light loss in the overlapping portion may be increased in somecases.

According to the light emitting device 100, the first gain region 140 issurrounded by the second gain region 160 and the first side surface 106a in the plan view. Thus, the length of the second gain region 160 canbe set to be greater than the length of the first gain region 140. Forexample, the first light generated in the first gain region 140 is bluelight, and the second light generated in the second gain region 160 isgreen light. Here, in some cases, the second active layer 112 providedwith the second gain region 160 for generating green light may be inlarge strain compared to the first active layer 106 provided with thefirst gain region 140 for generating blue light. Further, in some cases,a strong electrical field (piezoelectric field) caused by thepiezoelectric effect may be applied to the second active layer 112 dueto such strain, and the radiative recombination probability of electronsand holes may be degraded. In other words, the gain of green light maybe lower than that of blue light in some cases. According to the lightemitting device 100, as described above, the length of the second gainregion 160 can be set to be greater than the length of the first gainregion 140. Therefore, in the case in which the second light generatedin the second gain region 160 is the green light, the length of the gainregion of the green light with low gain can be made greater than that ofthe other color, and the intensity and the emission efficiency of greenlight can be increased. Therefore, in the case of using such a lightemitting device 100 to the projector, since the intensity and theemission efficiency of the green light having a high luminoussensitivity can be increased, a projector with higher luminous flux canbe realized.

According to the light emitting device 100, the first gain region 140 islocated below the end portion 123 of the second electrode 122, the endportion 123 being located near to the second gain region 160 side, andthe second gain region 160 is located below the end portion 125 of thethird electrode 124, the end point 125 being located near to the firstgain region 140 side. Therefore, the distance D1 between the firstemitting section 151 and the third emitting section 171 can more surelybe decreased. Similarly, the distance D2 between the second emittingsection 156 and the fourth emitting section 176 can be decreased. Thus,it is possible to more surely make the lights respectively emitted fromthe emitting sections 151, 171 enter a single collecting lens.Similarly, it is possible to make the lights respectively emitted fromthe emitting sections 156, 176 enter a single collecting lens.Therefore, according to the light emitting device 100, in the case ofusing the light emitting device 100 as the light source of theprojector, the number of the microlenses can more surely be reduced tothereby achieve the cost reduction.

2. Method of Manufacturing Light Emitting Device

Then, a method of manufacturing the light emitting device according tothe present embodiment will be explained with reference to theaccompanying drawings. FIGS. 6 and 7 are cross-sectional viewsschematically showing the manufacturing process of the light emittingdevice 100 according to the present embodiment, and each corresponds toFIG. 3.

As shown in FIG. 6, the first cladding layer 104, the first active layer106, the second cladding layer 108, the third cladding layer 110, thesecond active layer 112, and the fourth cladding layer 114 are grownepitaxially on the substrate 102 in this order. Thus, a laminated body131 can be formed. As the method of epitaxially growing the layers,there can be used, for example, a metal organic chemical vapordeposition (MOCVD) method, and a molecular beam epitaxy (MBE) method.

As shown in FIG. 7, the laminated body 131 is patterned to form thelaminated body 130 having the first portion 132, the second portion 134,and the third portion 136. The patterning is performed using, forexample, the photolithography technology and the etching technology.

As shown in FIG. 3, the insulating layer (not shown) is deposited on thelaminated body 130, and is then patterned to thereby form the insulatinglayer 116 provided with the openings 116 a, 116 b, and 116 c. Theinsulating layer is deposited using, for example, a chemical vapordeposition (CVD) method. The patterning is performed using, for example,the photolithography technology and the etching technology.

Then, the first electrodes 120, the second electrode 122, and the thirdelectrode 124 are formed on the first portion 132, the second portion134, and the third portion 136, respectively. In this process, firstly,a photo resist is patterned using the photolithography technology tothereby expose only the upper surface of the regions to be provided withthe electrodes, and cover the upper surface of the regions not to beprovided with the electrodes including the opening sections 30, 32, 34,and 36. Then, a conductive layer is evaporated on the entire surfaceusing a vacuum evaporation method. Then, the conductive layer on theregions not to be provided with the electrodes is removed (liftoff)together with the resist. The order of forming the electrodes 120, 122,and 124 is not particularly limited. In an example of the light emittingdevice 100, the electrodes 120 and the electrode 124, which areconnected to the layers with the same conductivity type, can be formedsimultaneously.

The light emitting device 100 according to the present embodiment can bemanufactured by the processes described hereinabove.

According to the method of manufacturing the light emitting device 100,it is possible to achieve simple layout of the wiring lines to beelectrically connected to the electrodes in installation and improve theflexibility of selecting the substrate material while achieving the costreduction.

3. Modified Examples of Light Emitting Device 3.1. Light Emitting DeviceAccording to First Modified Example

Then, a light emitting device according to a first modified example ofthe present embodiment will be explained with reference to theaccompanying drawings. FIG. 8 is a plan view schematically showing alight emitting device 200 according to the first modified example of thepresent embodiment. FIG. 9 is a cross-sectional view along the IV-IVline shown in FIG. 8 schematically showing the light emitting device 200according to the first modified example of the present embodiment. Itshould be noted that in FIGS. 8 and 9, the X axis, the Y axis, and the Zaxis are shown as the three axes perpendicular to each other.

Hereinafter, in the light emitting device 200 according to the firstmodified example of the present embodiment, the constituents thereofhaving the same functions as those of the constituents of the lightemitting device 100 according to the present embodiment will be denotedwith the same reference symbols, and the detailed explanation thereofwill be omitted.

As shown in FIG. 2, in the example of the light emitting device 100, thetwo first electrodes 120 are disposed, and the gain regions 140, 160(the electrodes 122, 124) are disposed between the two first electrodes120.

In contrast, in the light emitting device 200, the first electrodes 120are disposed so as to be surrounded by the first gain region 140 (thesecond electrode 122) and the side surface 130 a of the laminated body130 in the plan view as shown in FIG. 8.

According to the light emitting device 200, it is possible to reduce thesize in the Y-axis direction while keeping the length of the gainregions 140, 160, for example, compared to the light emitting device100. In other words, according to the light emitting device 200,downsizing can be achieved while keeping the length of the gain regions140, 160.

3.2. Light Emitting Device According to Second Modified Example

Then, a light emitting device according to a second modified example ofthe present embodiment will be explained with reference to theaccompanying drawings. FIG. 10 is a plan view schematically showing alight emitting device 300 according to the second modified example ofthe present embodiment. FIG. 11 is a cross-sectional perspective viewschematically showing the light emitting device 300 according to thesecond modified example of the present embodiment, and is an enlargedview of a region A surrounded by the thick dotted line shown in FIG. 10.It should be noted that in FIGS. 10 and 11, the X axis, the Y axis, andthe Z axis are shown as the three axes perpendicular to each other.

Hereinafter, in the light emitting device 300 according to the secondmodified example of the present embodiment, the constituents thereofhaving the same functions as those of the constituents of the lightemitting device 100 according to the present embodiment will be denotedwith the same reference symbols, and the detailed explanation thereofwill be omitted.

In the example of the light emitting device 100, the first gain region140 is surrounded by the second gain region 160 and the first sidesurface 106 a of the first active layer 106 in the plan view as shown inFIG. 2.

In contrast, in the light emitting device 300, the second gain portion144 of the first gain region 140 has a gap section 340 in which thesecond gain portion 144 is divided, and the fourth gain portion 162 ofthe second gain region 160 is disposed passing through the gap section340 in the plan view as shown in FIGS. 10 and 11.

The second electrode 122 is not formed above the gap section 340.Specifically, a part of the second electrode 122 located above thesecond gain portion 144 is divided, and the third electrode 124 isdisposed in the part in which the second electrode 122 is divided in theplan view.

According to the light emitting device 300, similarly to the lightemitting device 100, it is possible to simplify the layout of the wiringlines electrically connected to the electrodes when mounting and improvethe flexibility of selecting the substrate material.

It should be noted that although not shown in the drawings, the sixthgain portion 166 of the second gain region 160 can be disposed passingthrough the gap section 340 in the plan view instead of the fourth gainportion 162.

3.3. Light Emitting Device According to Third Modified Example

Then, a light emitting device according to a third modified example ofthe present embodiment will be explained with reference to theaccompanying drawing. FIG. 12 is a plan view schematically showing alight emitting device 400 according to the third modified example of thepresent embodiment. It should be noted that in FIG. 12, the X axis, theY axis, and the Z axis are shown as the three axes perpendicular to eachother.

Hereinafter, in the light emitting device 400 according to the thirdmodified example of the present embodiment, the constituents thereofhaving the same functions as those of the constituents of the lightemitting device 100 according to the present embodiment will be denotedwith the same reference symbols, and the detailed explanation thereofwill be omitted.

In the example of the light emitting device 100, as shown in FIG. 2, thesingle first gain region 140 and the single second gain region 160 aredisposed.

In contrast, in the example of the light emitting device 400, as shownin FIG. 12, a plurality of first gain regions 140 and a plurality ofsecond gain regions 160 are disposed. In the example shown in thedrawing, two first gain regions 140 are arranged along the Y axis, andthe two second gain regions 160 are arranged along the Y axis.

The number of the second electrodes 122 disposed and the number of theopening sections 30, 32 disposed each correspond to the number of thefirst gain regions 140. The number of the third electrodes 124 disposedand the number of the opening sections 34, 36 disposed each correspondto the number of the second gain regions 160. In the example shown inthe drawing, three first electrodes 120 are disposed, and one of thethree first electrodes 120 is disposed between the two second gainregions 160.

According to the light emitting device 400, a higher output can beachieved compared to the light emitting device 100.

4. Light Source Module

Then, a light source module according to the present embodiment will beexplained with reference to the accompanying drawings. FIG. 13 is a planview schematically showing the light source module 500 according to thepresent embodiment. FIG. 14 is a cross-sectional view along the XIV-XIVline shown in FIG. 13 schematically showing the light source module 500according to the present embodiment. FIG. 15 is a cross-sectional viewalong the XV-XV line shown in FIG. 13 schematically showing a lightsource module 500 according to the present embodiment. It should benoted that in FIG. 13, the light emitting devices 400 and amountingsubstrate 510 are shown in a simplified manner with a lens array 520 anda heatsink 530 omitted for the sake of convenience. Further, in FIG. 14,the light emitting devices 400 and the mounting substrate 510 are shownin a simplified manner. Further, in FIG. 15, the lens array 520 and theheatsink 530 are omitted. Further, in FIGS. 13 through 15, the X axis,the Y axis, and the Z axis are shown as the three axes perpendicular toeach other.

As shown in FIGS. 13 through 15, the light source module 500 can includethe mounting substrate 510, the lens array (the microlens array) 520,the heatsink 530, and the light emitting devices according to theembodiment of the invention. In the example described below, the lightsource module 500 including the light emitting devices 400 as the lightemitting device according to the embodiment of the invention will beexplained.

The light emitting devices 400 are mounted on the mounting substrate510. As shown in FIG. 15, the mounting substrate 510 can include asupport substrate 511, an insulating layer 512, and wiring lines 513,514, and 515.

As the support substrate 511, a silicon substrate, for example, is used.The support substrate 511 has a surface 511 a facing the light emittingdevices 400.

The insulating layer 512 is formed on the surface 511 a of the supportsubstrate 511. As the insulating layer 512, for example, an SiO₂ layeris used.

The insulating layer 512 is provided with the wiring lines 513, 514, and515. The wiring line 513 is electrically connected to the firstelectrode 120 via a bonding member 516. The wiring line 514 iselectrically connected to the second electrode 122 via the bondingmember 516. The wiring line 515 is electrically connected to the thirdelectrode 124 via the bonding member 516. It is also possible for thewiring lines 513, 514, and 515 to have shapes corresponding to theshapes of the electrodes 120, 122, and 124, respectively, in the planview. It is possible to inject current individually to each of theelectrodes 120, 122, and 124 using the wiring lines 513, 514, and 515.

As described above, the width of the electrodes 120, 122, and 124 is ina range of about 100 μm through 200 μm. Therefore, it is possible toprovide a sufficient contact area between each of the electrodes 120,122, and 124 and the bonding member 516. Thus, it is possible to preventthe bonding member 516 from running off the electrodes 120, 122, and 124before curing when bonding. Further, the bonding strength between theelectrodes 120, 122, and 124 and the wiring lines 513, 514, and 515 canbe increased. As the material of the wiring lines 513, 514, and 515,there can be cited, for example, copper, aluminum, and gold. As thematerial of the bonding member 516, there can be cited, for example,silver paste.

As shown in FIG. 15, it is also possible to dispose a bonding member 517between the insulating layer 116 of the light emitting device 400 andthe insulating layer 512 of the mounting substrate 510. The insulatinglayer 116 and the insulating layer 512 can be bonded with the bondingmember 517. Thus, the bonding strength between the light emittingdevices 400 and the mounting substrate 510 can be increased. As thematerial of the bonding member 517, there can be cited, for example,polysilsesquioxane (PSQ).

The light emitting devices 400 are mounted on the mounting substrate510. The light emitting devices 400 are each mounted in a junction-downstate. Specifically, the light emitting devices 400 are mounted so thatthe laminated body 130 side provided with the pin junction faces to themounting substrate 510 side (downward in FIG. 14) instead of thesubstrate 102 side. Thus, heat generated when injecting the current intothe light emitting devices 400 can promptly be released via the mountingsubstrate 510 and the heatsink 530 with high thermal conductivityinstead of the substrate 102.

As shown in FIGS. 13 and 14, a plurality of light emitting devices 400is disposed. In the example shown in the drawings, three light emittingdevices 400 are arranged along the X axis.

As shown in FIG. 14, the lens array 520 is supported by the mountingsubstrate 510. The material of the lens array 520 is, for example,glass. The lens array 520 can include transmitting surfaces (planes ofincidence of light) 521, reflecting surfaces 522, and collecting lenses(microlenses) 524.

As shown in FIG. 14, the transmitting surfaces 521 are eachperpendicular to the optical axes of the first light 20 and the secondlight 22 emitted from the light emitting device 400, when the emissiondirections of the lights 20, 22 are perpendicular to the side surface130 a. Further, the reflecting surface 522 is disposed so as to form anangle of 45° with the transmitting surface 521. It is also possible toprovide the transmitting surface 521 with an antireflection film and toprovide the reflecting surface 522 with a reflecting film. Thus, thelight loss in the transmitting surface 521 and the reflecting surface522 can be reduced.

As shown in FIG. 14, the light emitted from the light emitting device400 can be reflected by the reflecting surface 522 after transmittingthrough the transmitting surface 521. It should be noted that, when theemission direction of the first light 20 and the second light 22 is notperpendicular to the side surface 130 a, the direction of the opticalaxis is converted into a direction perpendicular to the side surface 130a by refracting the first light 20 and the second light 22 in thetransmitting surface 521, and thus, it is possible to reflect the firstlight 20 and the second light 22 by the reflecting surface 522. By thelight being reflected by the reflecting surface 522, the proceedingdirection of the light is deflected toward the collecting lens 524.

There is a plurality of collecting lenses 524. The collecting lenses 524are arranged two-dimensionally corresponding to the emitting sections151, 171 and the emitting sections 156, 176. At least some of thecollecting lenses 524 are each disposed at a position overlapping thetransmitting surface 521 and the reflecting surface 522 in the planview. Further, by disposing the transmitting surface 521 close to theemitting sections 151, 171 or the emitting sections 156, 176, thecollecting lenses 524 can be disposed at the position overlapping theemitting sections 151, 171 or the emitting sections 156, 176 in the planview as shown in FIG. 13. Thus, it is possible for the first light 20 asblue light and the second light 22 as green light, for example, to enterthe collecting lens 524 without enlarging the collecting lens 524. Sincethe radiation angle of the light having entered the collecting lens 524is controlled (collected, collimated, decreased in radiation angle, andso on), the light can be overlapped (partially overlapped). Thus, it ispossible to irradiate, for example, the liquid crystal light valve withuniformity.

The heatsink 530 is disposed on an opposite surface of the mountingsubstrate 510 to the surface thereof on which the light emitting devices400 are mounted. The heatsink 530 can be bonded to the mountingsubstrate 510. As the material of the heatsink 530, there can be cited,for example, copper, molybdenum, aluminum nitride, and boron oxide. Dueto the heatsink 530, the heat radiation property of the light emittingdevices 400 can be improved.

According to the light source module 500, it is possible to include thelight emitting devices 400 each having the electrodes 120, 122, and 124formed on one side of the laminated body 130. Therefore, the layout ofthe wiring lines 513, 514, and 515 electrically connected to theelectrodes 120, 122, and 124 can be simplified. Further, since themounting process can be made easy, improvement of the turn-around time(TAT) of the mounting process, and reduction of the mounting cost can beachieved.

According to the light source module 500, the first light 20 as bluelight and the second light 22 as green light, for example, are input tothe same collecting lens 524. Therefore, in the case of using the lightsource modules 500 as the light source of the projector, the number oflens arrays can be decreased to thereby achieve the cost reduction.

5. Projector

Then, a projector according to the present embodiment will be explainedwith reference to the accompanying drawings. FIG. 16 is a perspectiveview schematically showing a projector 600 according to the presentembodiment. FIG. 17 is a diagram schematically showing the projector 600according to the present embodiment. It should be noted that in FIG. 16,a housing 612, a heatsink 614, fans 616, 618 are omitted, and the lightsource module 500 is shown in a simplified manner for the sake ofconvenience. Further, in FIG. 17 the light source module 500 is shown ina simplified manner.

As shown in FIGS. 16 and 17, the projector 600 includes first lightsource module 602 GB, second light source module 602R, transmissiveliquid crystal light valves (light modulation devices) 604GB, 604R, anda projection lens (a projection device) 608. Further, the projector 600can include a dichroic prism (a colored light combining section) 606, ahousing 612, a heatsink 614, an intake fan 616, and an exhaust fan 618.

The housing 612 can house the light source modules 602GB, 602R, theliquid crystal light valves 604GB, 604R, the dichroic prism 606, and theheatsink 614.

The first light source module 602GB is configured using the light sourcemodule 500. In the example shown in the drawings, the first light sourcemodule 602GB is composed of the two light source modules 500 arranged inparallel to each other. The first light source module 602GB is capableof emitting green light and blue light. More specifically, the firstlight 20 (see FIG. 13) emitted from the emitting sections 151, 156 isblue light, and the second light 22 (see FIG. 13) emitted from theemitting sections 171, 176 is green light. The lights 20, 22 emittedfrom the emitting sections 151, 156, 171, and 176 are collected by thelens array 520 as described above.

The second light source module 602R is configured using the light sourcemodule 500. In the example shown in the drawings, the second lightsource module 602R is composed of the two light source modules 500arranged in parallel to each other. The second light source module 602Ris capable of emitting the red light. More specifically, the first light20 (see FIG. 13) emitted from the emitting sections 151, 156, and thesecond light 22 (see FIG. 13) emitted from the emitting sections 171,176 are red light. The lights 20, 22 emitted from the emitting sections151, 156, 171, and 176 are collected by the lens array 520 as describedabove. It should be noted that the second light source module 602R canbe formed of a light source module using light emitting devices eachhaving only the laminated body 130 formed by stacking only the firstcladding layer, the first active layer, and the second cladding layer,the first electrode electrically connected to the first cladding layer,and the second electrode connected to the second cladding layer, andeach generating or emitting only the first lights 10, 20.

The light source modules 602GB, 602R are disposed on the heatsink 614.The material of the heatsink 614 is, for example, copper and aluminum.The heat radiation property of the light source modules 602GB, 602R canbe improved by the heatsink 614.

The intake fan 616 and the exhaust fan 618 are provided to the housing612. The heat radiation property of the light source modules 602GB, 602Rcan be improved by the intake fan 616 and the exhaust fan 618.

The lights emitted from the light source modules 602GB, 602R (the lightswith the radiation angle controlled by the lens array) enter the liquidcrystal light valves 604GB, 604R, respectively. The liquid crystal lightvalves 604GB, 604R respectively modulate the incident lights inaccordance with image information. Then, the projection lens 608magnifies the images formed by the liquid crystal light valves 604GB,604R, and projects them on a screen 610. In the example shown in FIG.17, the projection lens 608 is provided to the housing 612.

The dichroic prism 606 is capable of combining the lights transmittingthrough the liquid crystal light valves 604GB, 604R and guiding thecombined light to the projection lens 608.

More specifically, the colored light modulated by each of the liquidcrystal light valves 604GB, 604R enters the dichroic prism 606. Theprism is formed of two rectangular prisms bonded to each other, and hasdielectric multilayer films for reflecting the blue light and the greenlight disposed on the inside surfaces thereof. The three colored lightsare combined by these dielectric multilayer films to thereby form thelight representing a color image. Then, the light thus combined isprojected on the screen 610 by the projection lens 608 as the projectionoptical system, and thus an enlarged image is displayed.

According to the projector 600, the first light source module 602GBcapable of emitting blue light and green light, and the second lightsource module 602R capable of emitting red light can be included.Therefore, the number of lens arrays and the number of liquid crystallight valves can be decreased compared to the projector including alight source module for emitting red light, a light source module foremitting green light, and a light source module for emitting blue lightrespectively. Thus, the cost reduction can be achieved in the projector600.

According to the projector 600, it is possible to dispose the lightsource modules 602GB, 602R immediately before the liquid crystal lightvalves 604GB, 604R, and simultaneously perform the collection and theuniform illumination using the collection lenses 524. Therefore, theloss in the optical system between, for example, the light sourcemodules 602GB, 602R and the liquid crystal light valves 604GB, 604R canbe reduced. Therefore, the projector 600 capable of reducing the powerconsumption, being small in size, and being good for the environment canbe realized.

It should be noted that in the example shown in FIG. 17, the projector600 has a single set of the light source modules 602GB, 602R, the liquidcrystal light valves 604GB, 604R, the dichroic prism 606, and theprojection lens 608. In contrast, as shown in FIG. 18, the projector 600can include two sets of the light source modules 602GB, 602R, the liquidcrystal light valves 604GB, 604R, the dichroic prism 606, and theprojection lens 608. Thus, 3D display becomes possible.

It should be noted that, although the transmissive liquid crystal lightvalves are used as the light modulation devices in the example describedabove, it is also possible to use light valves other than the liquidcrystal light valves, or to use reflective light valves. As such lightvalves, there can be cited, for example, reflective liquid crystal lightvalves and the Digital Micromirror Device™. Further, the configurationof the projection optical system is appropriately modified in accordancewith the type of the light valves used therein.

Further, it is also possible to apply the light source modules 602GB,602R to the light source device of a scanning type image display device(projector) for displaying an image with a desired size on a displaysurface or a screen by scanning the light from the light source.

The embodiment and the modified examples described above areillustrative only, and the invention is not limited thereto. Forexample, it is also possible to arbitrarily combine the embodiment andthe modified examples described above.

The invention includes configurations substantially the same (e.g.,configurations having the same function, the same way, and the sameresult, or configurations having the same object and the sameadvantages) as the configuration described as the embodiment of theinvention. Further, the invention includes configurations obtained byreplacing a non-essential part of the configuration described as theembodiment of the invention. Further, the invention includesconfigurations exerting the same functional effects and configurationscapable of achieving the same object as the configuration described asthe embodiment of the invention. Further, the invention includesconfigurations obtained by adding technologies known to the public tothe configuration described as the embodiment of the invention.

What is claimed is:
 1. A light emitting device comprising: a substrate;a laminated body formed by stacking a first cladding layer, a firstactive layer, a second cladding layer, a third cladding layer, a secondactive layer, and a fourth cladding layer on the substrate in thisorder; at least one first electrode electrically connected to the firstcladding layer; a second electrode electrically connected to the secondcladding layer and the third cladding layer; and a third electrodeelectrically connected to the fourth cladding layer, wherein the firstelectrode, the second electrode, and the third electrode are located onan opposite surface of the laminated body to the substrate, the firstactive layer generates first light in response to current injected usingthe first electrode and the second electrode, the second active layergenerates second light in response to current injected using the secondelectrode and the third electrode.
 2. The light emitting deviceaccording to claim 1, wherein at least one side surface of the firstactive layer included in a side surface of the laminated body having anormal line perpendicular to a stacking direction of the laminated bodyis provided with an emitting section from which the first light isemitted, and at least one side surface of the second active layerincluded in the side surface of the laminated body is provided with anemitting section from which the second light is emitted.
 3. The lightemitting device according to claim 2, wherein the first active layer hasa first gain region adapted to generate the first light in response tothe injection of the current, the first gain region includes a firstgain portion having a belt-like shape extending from a first emittingsection provided to a first side surface of the first active layer to afirst reflecting section provided to a second side surface of the firstactive layer, a second gain portion having a belt-like shape extendingfrom the first reflecting section to a second reflecting sectionprovided to a third side surface of the first active layer, and a thirdgain portion having a belt-like shape extending from the secondreflecting section to a second emitting section provided to the firstside surface, the second active layer has a second gain region adaptedto generate the second light in response to the injection of thecurrent, the second gain region includes a fourth gain portion having abelt-like shape extending from a third emitting section provided to afourth side surface of the second active layer to a third reflectingsection provided to a fifth side surface of the second active layer, afifth gain portion having a belt-like shape extending from the thirdreflecting section to a fourth reflecting section provided to a sixthside surface of the second active layer, and a sixth gain portion havinga belt-like shape extending from the fourth reflecting section to afourth emitting section provided to the fourth side surface, the firstside surface and the fourth side surface constitute apart of the sidesurface of the laminated body having the normal line perpendicular tothe stacking direction of the laminated body, and the first lightemitted from the first emitting section, the first light emitted fromthe second emitting section, the second light emitted from the thirdemitting section, and the second light emitted from the fourth emittingsection are emitted in a same direction.
 4. The light emitting deviceaccording to claim 3, wherein the first gain region and the second gainregion each have a bracket shape when viewed from the stacking directionof the laminated body.
 5. The light emitting device according to claim2, wherein a wavelength of the first light is no smaller than 435 nm andno larger than 485 nm, and a wavelength of the second light is nosmaller than 485 nm and no larger than 570 nm.
 6. The light emittingdevice according to claim 3, wherein the first gain region and thesecond gain region fail to overlap each other when viewed from thestacking direction of the laminated body.
 7. The light emitting deviceaccording to claim 3, wherein the second gain portion of the first gainregion includes a gap section where the second gain portion is divided,and the fourth gain portion of the second gain region is disposed so asto pass through the gap section when viewed from the stacking directionof the laminated body.
 8. The light emitting device according to claim3, wherein the first gain region is surrounded by the second gain regionand the first side surface when viewed from the stacking direction ofthe laminated body.
 9. The light emitting device according to claim 3,wherein the second electrode has a surface larger than the first gainregion to cover the first gain region when viewed from the stackingdirection of the laminated body, the third electrode has a surfacelarger than the second gain region to cover the second gain region whenviewed from the stacking direction of the laminated body, the first gainregion is located below an end portion of the second electrode, the endportion being located near to the second gain region, and the secondgain region is located below an end portion of the third electrode, theend portion being located near to the first gain region.
 10. A projectorcomprising: the light emitting device according to claim 1; a lightmodulation device adapted to modulate the lights emitted from the lightemitting device in accordance with image information to form an image;and a projection device adapted to project the image formed by the lightmodulation device.
 11. A projector comprising: the light emitting deviceaccording to claim 2; a light modulation device adapted to modulate thelights emitted from the light emitting device in accordance with imageinformation to form an image; and a projection device adapted to projectthe image formed by the light modulation device.
 12. A projectorcomprising: the light emitting device according to claim 3; a lightmodulation device adapted to modulate the lights emitted from the lightemitting device in accordance with image information to form an image;and a projection device adapted to project the image formed by the lightmodulation device.
 13. A projector comprising: the light emitting deviceaccording to claim 4; a light modulation device adapted to modulate thelights emitted from the light emitting device in accordance with imageinformation to form an image; and a projection device adapted to projectthe image formed by the light modulation device.
 14. A projectorcomprising: the light emitting device according to claim 5; a lightmodulation device adapted to modulate the lights emitted from the lightemitting device in accordance with image information to form an image;and a projection device adapted to project the image formed by the lightmodulation device.
 15. A projector comprising: the light emitting deviceaccording to claim 6; a light modulation device adapted to modulate thelights emitted from the light emitting device in accordance with imageinformation to form an image; and a projection device adapted to projectthe image formed by the light modulation device.
 16. A projectorcomprising: the light emitting device according to claim 7; a lightmodulation device adapted to modulate the lights emitted from the lightemitting device in accordance with image information to form an image;and a projection device adapted to project the image formed by the lightmodulation device.
 17. A projector comprising: the light emitting deviceaccording to claim 8; a light modulation device adapted to modulate thelights emitted from the light emitting device in accordance with imageinformation to form an image; and a projection device adapted to projectthe image formed by the light modulation device.
 18. A projectorcomprising: the light emitting device according to claim 9; a lightmodulation device adapted to modulate the lights emitted from the lightemitting device in accordance with image information to form an image;and a projection device adapted to project the image formed by the lightmodulation device.
 19. A projector comprising: the super-luminescentdiode according to claim 18; a light modulation device adapted tomodulate the lights emitted from the super-luminescent diode inaccordance with image information to form an image; and a projectiondevice adapted to project the image formed by the light modulationdevice.